1. Field of the Invention
The present invention relates to a display device, and more particularly to a multi-mode stereoscopic image display method and apparatus wherein a plane picture and a stereoscopic picture can be displayed on a single display device.
2. Description of the Related Art
Generally, a display device is classified into a plane picture display device for displaying an image obtained by photographing an object using a single camera and a stereoscopic picture display device for combining two images obtained by photographing an object using two cameras positioned at different angles with respect to the same object to display an image.
The plane picture display device permits an observer to view a plane picture without a cubic effect because an identical picture is simultaneously incident to a left-eye and a right-eye of an observer.
On the other hand, the stereoscopic picture display device displays a picture being incident to the left-eye of an observer, hereinafter referred to as “left-eye picture” and a picture being incident to the right-eye of an observer, hereinafter referred to as “right-eye picture”, on a screen at the same time. The observer feels a cubic effect because he observes a picture displayed on the stereoscopic picture display device in a state in which the left-eye picture is combined with the right-eye picture. Such a stereoscopic picture display device includes a system that requires glasses for viewing and a system that does not require glasses for viewing.
Referring to FIG. 1, a stereoscopic picture display device requiring glasses includes first and second cameras 2a and 2b for photographing an object at a different angle, a display unit 14 for separating color signals of an image received from the first and second cameras 2a and 2b, and glasses 6 to be worn by an observer.
The first camera 2a photographs an object into red(r1), green(g1) and blue(b1) color images, and sends a video signal corresponding to the red color r1 to the display unit 14. The second camera 2b photographs an object into red(r2), green(g2) and blue(b2) color images at an angle different from the first camera 2a, and sends a video signal corresponding to the green color g2 and the blue color b2 to the display unit 14.
The display unit 14 displays a color picture using the red(r1), green(g2) and blue(b2) video signals received from the first and second cameras 2a and 2b. The glasses 6 include a left-eye lens and a right-eye lens. The left-eye lens is comprised of a red filter passing only a red color while the right-eye lens is comprised of a cyan filter passing only green and blue colors.
Since an observer views a red picture photographed by the first camera 2a via the red filter and green and blue pictures photographed by the second camera 2b via the cyan filter at the same time by his left and right eyes, respectively, he observes the same object at a different angle by his left and right eyes. Accordingly, the observer recognizes a picture displayed on the display unit 14 as a stereoscopic picture because the left-eye picture is combined with the right-eye picture in his head.
Meanwhile, the glasses 6 may be comprised of a single color filter other than the red filter and a complementary color filter or the single color filter. For example, the glasses 6 may consists of a green filter and a magenta filter, or a blue filter and a yellow filter.
However, the stereoscopic picture display device shown in FIG. 1 not only causes an observer an inconvenience in that he must wear glasses, but also it has a problem in that it is difficult to display and observe a stereoscopic picture having the original color of an object.
FIG. 2 and FIG. 3 illustrate a conventional stereoscopic display device that does not require glasses.
Referring to FIG. 2, the stereoscopic display device includes a display unit for displaying images from first and second cameras (not shown) alternately in a pixel unit, and a parallax barrier 22 opposed to a display screen of the display unit 24.
The display device 24 receives video signals from the first and second cameras photographing an object at a different angle. A first pixel P1 and a second pixel P2 of the display unit 24 are arranged in such a manner to be alternated with each other. A video signal inputted from the first camera is displayed on the first pixel P1 while a video signal inputted from the second camera is displayed on the second pixel P2. Herein, the first and second pixels P1 and P2 display a picture by three initial colors including red, green and blue sub-pixel cells, unlike the display unit 14 of FIG. 1.
The parallax barrier 22 is arranged in such a manner to interact with the first and second pixels P1 and P2 of the display unit 24, and includes an opaque filter 22a and transparent filters 22L and 22R that are alternated with each other. The opaque filter 22a and the transparent filters 22L and 22R provided at the parallax barrier 22 may be arranged in a stripe shape or in a mosaic shape. In the adjacent transparent filters 22L and 22R, the first transparent filter 22L, positioned at the left side, transmits light inputted from the first pixel P1 toward the left-eye EL of an observer. The second transparent filter 22R transmits light inputted from the second pixel P2 into the right-eye ER of an observer. The opaque filter 22a arranged between the first and second transparent filters 22L and 22R shuts off light inputted from the first pixel P1 and then progressed into the right-eye ER of an observer, and shuts off light inputted from the second pixel P2 and then progressed into the left-eye EL of an observer.
Since the right-eye picture and the left-eye picture are separated by the parallax barrier 22 in this manner, an observer views only a picture at the first pixel P1 via his left-eye EL, and only a picture at the second pixel P2 at his right-eye ER. Accordingly, the observer views a picture photographed at different angles at the same time via his left-eye EL and his right-eye ER, so that he recognizes a picture displayed on the display unit 24 as a stereoscopic picture.
However, the stereoscopic picture display device shown in FIG. 2 has a deterioration in brightness caused by the opaque filter 22a. Furthermore, brightness deterioration becomes worse because the number and the density of the opaque filter 22a are increased for implementation of a wider viewing angle.
In order to overcome brightness deterioration of such a parallax barrier 22, there has been suggested a stereoscopic picture display device employing a color barrier in which the opaque filter 22a does not exist.
Referring to FIG. 3, the stereoscopic picture display device employing a color barrier includes first and second cameras 32a and 32b for photographing an object at different angles, an image signal converter 36 for converting images inputted from the first and second cameras 32a and 32b into a stereoscopic image format to send the same to a display unit 34, and a color barrier 38 opposed to the display screen of the display unit 34.
The image signal converter 36 combines video signals received from the first and second cameras 32a and 32b such that the video signals inputted from the first and cameras 32a and 32b are arranged alternately, to thereby convert them into a stereoscopic picture format.
A mixed image signal from the image signal converter 36 is inputted to the display unit 34. Each of the first and second pixels P1 and P2 of the display unit 34 includes red, green and blue sub-pixel cells. A red video signal r1 from the first camera 32a and green and blue video signals g2 and b2 from the second camera 34a are displayed on the first pixel P1 of the display unit 34. On the other hand, a red video signal r2 from the second camera 32b and green and blue video signals g1 and b1 from the first camera 32a are displayed on the second pixel P2 of the display unit 34.
The color barrier 38 includes red filters 38R1 and 38R2 and a cyan filter, which interact with the first and second pixels P1 and P2 and are alternated with each other. The first red filter 38R1 positioned at the left side of the adjacent red filters 38R1 and 38R2, transmits a red light r1 inputted from the first pixel P1 toward the left-eye of an observer while shutting off light having other wavelength bands. On the other hand, the second red filter 38R2 positioned at the right side transmits red light r2 inputted from the second pixel P2 toward the right-eye of an observer while shutting off light having other wavelength bands. The cyan filter 38C arranged between the first and second red filters 38R1 and 38R2 shuts off red light, and transmits green and blue lights g2 and b2 inputted from the first pixel P1 toward a right-eye ER of an observer while transmitting green and blue lights g1 and b1 toward the left-eye EL of an observer.
In the meantime, the color barrier 38 may be comprised of a green filter and a magenta filter, or a blue filter or a yellow filter rather than a red filter and a cyan filter.
Since the right-eye picture and the left-eye picture are separated by the color barrier 38 in this manner, an observer views only a picture at the first pixel P1 via his left-eye EL and only a picture at the second pixel P2 at his right-eye ER. Accordingly, the observer views a picture photographed at different angles at the same time via his left-eye EL and his right-eye ER, so that he recognizes a picture displayed on the display unit 34 as a stereoscopic picture.
Such a conventional stereoscopic picture display device has a problem in that, since all images are displayed by a stereoscopic picture independently of a kind of picture and a user's selection, they have more deterioration in definition than a plane picture upon displaying text information or a stationary picture. Accordingly, there is a need for a stereoscopic picture display device that is capable of selectively displaying a plane picture and a stereoscopic picture depending based upon a user's selection of the kind of picture desired.